tabbed-view changes in version 1.7

[ChrisHaller]

I use woocommerce-pos in a very small shop.
Since version 1.7, the limit at which products and shopping cart are displayed in tabs instead of side by side has been set from 768px to 640px.
This is not ideal for my purposes. That's why I wanted to set the value back to 768px. Unfortunately, I can't find this location anywhere in the source code (css and php).
Can anyone give me a hint?